Muon g-2 magnet ring move and celebration today

The Muon g-2 ring will take the above-marked path across Fermilab today. Also marked are today's restricted parking areas. Viewing areas will be set up in front of Wilson Hall. Carpooling is encouraged for people coming to Wilson Hall.

Fermilab will celebrate the arrival of the Muon g-2 magnet ring today at 5:30 p.m. at Wilson Hall. Fermilab employees, users, their families and our neighbors are invited to watch as Emmert International transports the magnet across Fermilab grounds.

The magnet is expected to pass near Wilson Hall at 6:30 p.m, and viewing areas will be set up in front of the building. A group photo with the ring and all people present will be taken around 7 p.m.

Rain and thunderstorms are forecasted for this evening. Regardless of weather conditions, the indoor portion of the event will go on, beginning at 5:30. This will include hands-on science activities in Wilson Hall and the opportunity to ask scientists questions about the Muon g-2 experiment. The ring will move rain or shine and will be delayed only in the event of lightning. Bring rain gear, and check the Big Move Web page for updates. We will post updates on the Fermilab Today Twitter account.

The above map details both the route of the magnet ring and parking availability throughout the site today. Because of the magnet transport, certain parking areas will be blocked off all day, and others will be closed starting at 4 p.m. Please make note of these areas and plan accordingly. Those coming on site to see the move are encouraged to carpool.

Video of the Day

Final night of Muon g-2 ring land journey to Fermilab

This 2-minute video shows highlights from the third and final leg of the Muon g-2 ring's land journey to Fermilab. View the video. Video: Fermilab

From symmetry

Giant electromagnet arrives at Fermilab

The 50-foot-wide electromagnet for the Muon g-2 experiment has completed its five-week journey from New York to Illinois. Photo: Reidar Hahn

For the last three nights, a big rig has traveled slowly down the roads of suburban Illinois bearing an American flag and the warning sign "Oversize Load." The warning may have been an understatement.

Its "load" was a 50-foot, 17-ton electromagnet that, for the last month, has voyaged by land and by sea from Brookhaven National Laboratory on Long Island. Early this morning, it reached its final destination: Fermi National Accelerator Laboratory outside of Chicago.

The electromagnet arrived accompanied by an impressive entourage: a dozen state trooper cars and more than a handful of county sheriffs and local police, plus crews from a company called Roadsafe, which was tasked with removing roadside signs ahead of the convoy and righting them after it passed. It will make its final move across the laboratory site this afternoon.

The logistics of the move have captured imaginations all along the way. But underneath the spectacle is important, potentially groundbreaking science.

The electromagnet is part of what is known as the Muon g-2 experiment. Scientists on the Muon g-2 experiment study short-lived particles called muons, which wobble when placed in a magnetic field due to an internal conflict between some of their characteristics.

In 2001, Brookhaven scientists used the ring to measure that wobble. Taking into consideration their current understanding of physics, scientists can predict what it should be like. If it turns out to be different than expected, it could indicate the presence of new physics.

In the first iteration of this experiment, Brookhaven physicists found hints that the wobble was off. Relocating the experiment to Fermilab will allow it to run in a more intense particle beam (for less money than it would cost to build the experiment anew), giving a more precise answer.

"We've been trying for years to really determine whether we've discovered something new and exciting," says Muon g-2 Spokesperson Lee Roberts, who began working on the experiment in 1984. "We're all excited to see the answer. It's exciting for me personally, and it's exciting for science."

Dark-matter hunt appears to be zeroing in on a leading contender

From Wired, July 22, 2013

Pity the poor physicist searching for dark matter, the exotic substance that accounts for roughly one-quarter of all the stuff in the cosmos, yet only interacts with the rest of the universe through gravity and the weak nuclear force. Hardly a week goes by, it seems, without a tantalizing new hint of a dark matter particle hovering at the threshold of statistical significance that eventually goes poof, dashing hopes yet again.

R-parity violation

Not only would the discovery of supersymmetry double the number of known particles, but it would introduce a new type of charge: Standard Model particles have positive R-parity and supersymmetric particles have negative R-parity.

Many of the CMS results presented in this column involve supersymmetry, the idea that there is a deep relationship between matter and forces. If nature is supersymmetric, then for each type of matter particle, there would be a corresponding supersymmetric force, and for each of the four forces, there would be a corresponding particle of supersymmetric matter. No evidence of supersymmetry has yet been found, despite the fervent searches, so you might be wondering why scientists are still looking for it. There are two reasons: (1) It would greatly increase our understanding of how all known particles unify, and (2) there are so many different ways that supersymmetry might manifest itself that the searches performed so far are not exhaustive.

To illustrate this complexity, let's examine one property that a supersymmetric theory might or might not have, known as R-parity. R-parity is a property of particles in the same sense as electric charge. Just as protons are positively charged and electrons are negatively charged, all currently known particles have positive R-parity, and their supersymmetric variants, if they exist, would have negative R-parity. R-parity is the supersymmetric-ness of a particle. Supersymmetric theories come in two broad classes: those in which the R-parity of a system is constant, like electric charge, and those in which R-parity can change with time.

Not only would the constancy or variation of R-parity reveal something fundamental about supersymmetry, but it has implications for the way scientists search for it. If R-parity is constant, then at least one supersymmetric particle must be stable. It cannot decay into normal matter because that would flip its R-parity from negative to positive. This feature could explain dark matter, because the stable supersymmetric particle would be dark (invisible). It also means that supersymmetric particles would appear as missing energy in a particle detector like CMS, due to their invisibility. Most searches for supersymmetry look for this characteristic energy imbalance.

If, on the other hand, R-parity is not constant, then all supersymmetric particles could decay, and searches based on missing energy would not find them. For this reason, a team of CMS physicists performed a different kind of supersymmetry search, one that doesn't rely on missing energy. They used lepton count, b quark identification and the distribution of energy to distinguish supersymmetric events from the background.

What they measured is consistent with known physics, further rolling back uncertainty with hard data. When dealing with the unknown, one must leave no stone unturned.

—Jim Pivarski

The physicists pictured above performed a search for R-parity violating supersymmetry.

These U.S. physicists were involved in setting up a cleanroom at CERN to test CMS pixel detectors. The cleanroom allows scientists to fully test the equipment.

Photo of the Day

Recycler cavities and the Main Injector 60 RF section

The Accelerator Division recently installed these two 53-MHz cavities in the Recycler in preparation for the imminent startup of beam to the Main Injector. Photo: Marty Murphy, AD